We plan to synthesize and have tested a selection of N-nitrosoamides, N-nitrosocarbamates, and N-nitrosoureas and several of the corresponding N-nitro compounds. These compounds are designed to form carbonium ions in solution, ions which are probably the active species in the carcinogenic and anti-cancer reactivities of the chloroethylnitrosoureas; we plan to examine new types of precursors which will deliver new types of carbonium ions. Diazotates, nitrososulfamates, and nitrosoamides of amino acids will be examined with the goal in mind of separating the anti-cancer and mutagenic activities. Attention will be paid to the mechanism of carbonium ion formation by these compounds. The compounds will be tested for carcinogenicity, mutagenicity, and anti-cancer activity.